1. Field of the Invention
The invention relates to data acquisition and analysis systems and, more particularly, to a system for real-time acquisition and analysis of a two-dimensional array of data regarding a phenomenon such as a plasma within a plasma generator including plasmas generated in semiconductor processing equipment, liquid crystal display fabrication equipment or other such equipment.
2. Description of the Background Art
In many types of substrate processing techniques, including etching, physical vapor deposition, liquid crystal display fabrication, chemical vapor deposition, and the like, the processing equipment utilizes a plasma during substrate processing. To optimize the process, the plasma must be maintained uniformly across the entire surface of the substrate being processed. To characterize a plasma and to determine particular parameters for establishing and maintaining the plasma, the plasma must be monitored in some manner while processing an actual substrate or a substrate facsimile. When the plasma is used in semiconductor wafer processing, the plasma is typically monitored while processing an actual wafer or a placebo wafer (also known as a dummy wafer).
One simple technique for monitoring the plasma uniformity within a semiconductor processing system requires placing an actual wafer in a reaction chamber of an etching system such as a model PE5000 manufactured by Applied Materials, Inc. of Santa Clara, Calif. The plasma initialization and maintenance parameters, e.g., gas pressure, source power, bias power, cathode temperature, and the like, are established and then the equipment strikes the plasma. The equipment is used in a manner that duplicates utilization of the plasma to process the wafer. After the processing is complete, the wafer is removed and physically inspected to determine the uniformity of the processing. For example, if an etch process was accomplished, the uniformity of the etch is measured using a laser interferometer. The resulting physical properties of the wafer are used to approximate the uniformity of the plasma. By repeating this technique for a number of wafers using various plasma parameters, the optimal parameter set can be determined which produces the optimal plasma uniformity. However, this plasma monitoring and evaluation technique is time consuming and costly.
Another technique used to monitor plasma uniformity is to attach one or more ion current probes to a placebo or dummy wafer, position the dummy wafer in the reaction chamber, and strike a plasma. A current meter measure the current generated by each of the ion current probes as a plasma is generated proximate the placebo wafer. The current measured represents the plasma density near the probes. As such, comparing the data from a number of probe locations generally represents the uniformity of the plasma. To compute uniformity, this technique requires substantial post acquisition processing of the data collected from the probes.
Therefore, there is a need in the art for a system for monitoring and evaluating a three-dimensional phenomenon such as a plasma such that a graphical representation of the phenomena is generated and displayed. Also, such display generation should be accomplished in real-time such that instantaneous analysis and optimization of the phenomenon control parameters can be accomplished.